As transnational organized crime increasingly presents a national security threat throughout Latin America, governments must re-examine the roles and responsibilities of their security forces, both military and police, to ensure the welfare, security, prosperity and sovereignty of their countries. To reduce drug-related violence per-petrated by the Mexican cartels, President Felipe Calderón deployed the military to complement police efforts across Mexico in 2006; after 10 years of the armed forces countering the cartels, there is a heated debate over how the military and police should be engaged in internal security as homicides are on the rise. In 2011, the US issued a national strategy to combat transnational organized crime recognizing the seriousness of the threats from transnational criminal organizations (TCOs) to the Americas. As Colombia transitions from fighting the decades-long FARC armed insurgency to implementing the peace accord in the “post-conflict” era, countering transnational organized crime has become a top priority and will entail an evolving role of the police and military to fight TCOs. Governments will need a strong legal framework, clearly defined missions for the military and police, specialized training, and talent recruitment and retention to realize security sector reform to counter transnational organized crime effectively across the Americas.